RBSE Class 8 Science Important Questions Chapter 17 Stars and The Solar System

Rajasthan Board RBSE Class 8 Science Important Questions Chapter 17 Stars and The Solar System Questions and Answers.

RBSE Class 8 Science Chapter 17 Important Questions Stars and The Solar System

Objective Questions

Question 1.
The movement of stars is seen from? 
(a) West to East 
(b) East to West 
(c) North to South
(d) South to North
Answer:
(b) East to West

Question 2.
Nearest planet to sun is     
(a) Pluto    
(b) Venus
(c) Saturn    
(d) Mercury
Answer:
(d) Mercury

Question 3.
Which planet is known as the red planet?
(a) Mars    
(b) Mercury
(c) Venus    
(d) Saturn
Answer:
(a) Mars    

Question 4.
India’s first artificial satellite?
(a) INSAT-1    
(b) I.R.S.- 1
(c) Aryabhatta    
(d) Kalpana- 1
Answer:
(c) Aryabhatta

Question 5.
The largest planet of solar family is 
(a) Mercury    
(b) Jupiter
(c) Saturn    
(d) Venus
Answer:
(b) Jupiter

Fill in the blanks

1. Solar system has ........................... planets.
Answer:
8

2. ........................... is our nearest star.
Answer:
sun

3. Density of ........................... planet is less than even the density of water.
Answer:
Saturn

4. One of the famous constellation is ...........................  which is seen in the first part of night.
Answer:
Ursa Major

True/False

Mark True (T) or False (F) to the following statements

1. Mercury is the farthest planet of solar system.
Answer:
False

2. Earth is an inner planets.
Answer:
True

3. Evening star is an artificial satellite.
False

4. Venus does not have any satellite of its own in the solar system.
Answer:
True

Match the words given in 'Column-A' with 'Column-B'

Question 1. 

Column-A	Column-B
(i) Sirius	(a) Seen during winter in late evenings
(ii) Cassiopeia	(b) Visible during summer in early part of the night
(iii) Great bear	(c) Visible during wdnter in early part of the night
(iv) Orion	(d) Brightest star

Answer:

Column-A	Column-B
(i) Sirius	(d) Brightest star
(ii) Cassiopeia	(c) Visible during wdnter in early part of the night
(iii) Great bear	(a) Seen during winter in late evenings
(iv) Orion	(b) Visible during summer in early part of the night

Question 2. 

Column-A	Column-B
(i) Saturn	(a) Nearest to earth
(ii) Jupiter	(b) Largest planet
(iii) Mercury	(c) Least dense
(iv) Venus	(d) Nearest to sun

Answer:

Column-A	Column-B
(i) Saturn	(c) Least dense
(ii) Jupiter	(b) Largest planet
(iii) Mercury	(d) Nearest to sun
(iv) Venus	(a) Nearest to earth

Very Short Answer Type Questions

Question 1. 
What do you mean by phases of moon? 
Answer:
The various shapes of the bright part of the moon as seen during a month are called phase of die moon.

Question 2. 
Define light year?
Answer:
Distance travelled by light in one year is called light year.

Question 3. 
What is the speciality of pole star? 
Answer:
It is present in the direction of earth’s axis of rotation and does not seem to move. It remains stationary in the north.

Question 4. 
Name two planets situated between sun and the earth.
Answer:

• Mercury 
• Venus 

Question 5. 
What do you mean by inner planets? 
Answer:
Planets present near the sun like Mercury, Venus, Earth and Mars are called inner planets.

Question 6. 
Name the outer planets.
Answer:
Outer planets are Jupiter, Saturn, Uranus and Neptune.

Question 7. 
What are asteroids?
Answer:
There is a large gap between the orbits of Mars and Jupiter. A large number of small objects (rocky material) which also move around sun are called asteroids.

Question 8. 
What is a meteor? Why is it seen for only a short period?
Answer:
A meteor is a part of asteroid or comet. Due to friction of atmosphere, it heats up evaporates quickly and therefore is seen brightly only for a short time.

Question 9. 
What are meteorites?
Answer:
Large meteors that are not completely evaporated due to friction collide with the earth, are called meteorites.

Question 10. 
What do you mean by remote sensing? 
Answer:
Obtaining information about an object from a distance, without touching it, is called remote sensing.

Short Answer Type Questions

Question 1. 
Explain why only one face of moon is visible to the earth?
Answer:
Time period of one revolution by moon around the earth is equal to time period of moon's one rotation.about its own axis. Therefore, only one face of moon is visible towards the earth. We can understand it with the following activity:

Draw a circle of radius 1 m on the ground. Ask one of your friends to stand on the centre of the circle? Revolve around your friend in such a manner that your face always remains towards your friend. Can your friend see your back? Moon revolves round the earth in a similar manner?

Question 2. 
What do you mean by Baby Moon? 
Answer:
We know that on full moon day, moon is visible as a complete circle. After that, the illuminated part of the moon keeps on decreasing. On the 15th day, we can’t see the moon. This day is called No Moon Day. Next day, a small part of the moon is visible in the sky, called the Baby moon. After this, the moon again gets bigger daily.

Question 3. 
Which star is the nearest to earth except the sun? How many light years far is that star?
Answer:
After sun, the nearest star to earth is Alpha Centauri. Its 4.3 light years away from the earth.

Question 4. 
What do you know about constellation Ursa Major?
Answer:
Ursa Major is a popular constellation visible in the first half of summer’s night. This constellation is also known as ‘Big Dipper’, ‘Great Bear’ or ‘Saptarishi’. It has seven clear stars. It seems like a big spoon or question mark. The handle of this spoon has three, while front part has four stars.

Question 5. 
Write qualities of Orion?
Answer:
Orion is visible in the midnight of winters. It is counted as most magnificent constellation of the sky. It has seven or eight bright stars. Orion is also called 'hunters'. Its middle three stars resemble a hunter’s belt. Four bright stars are arranged in the form of a quadrilateral. The brightest star of the sky - Sirius is near Orion. To locate sirius, imagine a straight line passing through the three middle stars of Orion.

Question 6. 
What do you know about constellation cassiopeia?
Answer:
Cassiopeia is a major constellation of the north sky, visible in the first half of winter’s night. It seems as a distorted alphabet W or M.

Question 7. 
In which part of the sky and at what time the following stars and constellations are visible?
Answer:
Saptarishi, Pole Star, Orion:

• Saptarishi is found in North part of the sky in summers.
• Pole star is visible throughout the year and is directly overhead the north pole.
• Orion is found in North - East part of sky, in winters.

Question 8. 
Except pole star, all stars seem to move from east to west. Why?
Answer:
The movement of stars is only seen due to rotation of earth on its axis. Earth on its axis rotates from west to east, due to which we see stars moving in the opposite directon (East - West). We see pole star stationary because it is present right above the rotatory axis of earth which remains at a fixed place and does not change with time.

Question 9. 
Name the members of solar system. How are their movement co - ordiated? 
Answer:
Sun is the head of the solar family. The solar family has eight members whose names are Mercury, Venus, Earth, Mass, Jupiter, Saturn, Uranus, Neptune. Other than this, minor planets, asteroids, comets and meteors are also present in groups.
Their movement is co - ordinated by gravitational attractional force of sun.

Question 10. 
Our earth is the most unique planet of solar system. Why?
Answer:
Earth is the only planet of solar system where life is developed and exists. The existence of life on earth makes it a unique planet.

Question 11. Write differences between star and planet. 
Answer:

Star	Planet
1. They have their own light.	1. They do not have light of their own. They are brightened because they reflect light from the sun.
2. Stars are very large. They appear small              due to large distance between earth and stars	2. Planets are very small comparable to stars.
3. Stars are infinite in number.	3. Major planets are only eight.
4. Stars twinkle at night.	4. Planets never twinkle.

Question 12. 
What is comet? Write.
Answer:
It is also a member of the solar family. They revolve around the sun in parabolic orbits. But their time period for revolution is generally very large. Generally, comets are of shiny heads and long tails. When a comet comes near the sun, its tail size becomes bigger. The tail of a comet is always away from the sun. Halley's comet is one such comet which is seen once in every 76 year. It was last seen in 1986.

Question 13. 
Give two differences between asteroids and meteors.
Answer:
1. Asteroids are parts of small rocks, that revolve round the earth, mainly between Mars and Jupiter, whereas meteors are small rocks of asteroids or comets.

2. Asteroids are mainly present between mars and Jupiter, while meteors may also enter the earth's atmosphere and be visible as shooting star.

Question 14. 
What are artificial satellites? What is their use?
Answer:
Artificial satellites are man made. They are launched from the earth. They revolve round the earth and nearer as that comparable to the moon which is natural satellite of the earth. India has built and launched many artificial satellites. Aryabhatta was the first Indian satellite. Some other Indian satellites are INSAT, IRS, Kalpana-I, EDUSAT etc.

Use:
Artificial satellites have many practical applications. They are used for forecasting weather, transmitting television and radio signals. They are used for telecommunication and remote sensing.

Question 15. 
What is the reason behind the fact that many meteorites fall on the surface of moon where as few meteorites fall on the surface of earth?
Answer:
Meteorites falling on moon are more because there is no atmosphere on the moon that can evaporate meteors by burning them due to friction. Thereby, all meteorites falling from space, reach the moon. In contrast, earth has its own atmosphere. Meteorites falling from space on entering the atmosphere, bum and evaporate completely. Thereby, only a few meteorites falling from space, reach the earth.

Essay Type Questions

Question 1. 
What are inner planets? What do you know about them?
Answer:
Planets near earth are called inner planets. These are four in number:
1. Mercury: It is the smallest planet and nearest to the sun. This is the reason why it is tough to see it. It can be seen just before sunrise or just after sunset at the horizon. It has no satellites.

2. Venus: It is earth's neighbour. It is the brightest planet at night. It sometimes is visible in east sky before sunrise and sometimes in western sky after sunset. Therefore, it is called morning or evening star, although it is not a star.

3. Earth: It is the only planet where life exists. Its environmental conditions are such that support life. As seen from space, due to the reflected light from sun, it is visible as Blue - Green. Its rotatory axis is not perpendicular to its orbital plane. It is tilted on its axis which is responsible for change in seasons. Moon is the satellite of earth.

4. Mars: First planet after earth’s orbit is Mars. It is of light red colour and therefore is also called red planet. It has two small natural satellites.

 
Question 2. 
What are outer planets? How many are they? Explain each in short.
Answer:
Planets outside orbit of Mars are called outer planets. They are four in number:
1. Jupiter: It is the largest planet of solar system. Its mass is 318 times larger than the earth. It rotates with high speed on its axis. It has many satellites. Around it are present feint rings. It can be seen easily as it is very bright.

2. Saturn: After Jupiter is Saturn i.e. pale yellow in colour. What makes it unique in the solar system are its beautiful rings. These rings can be easily observed by a small telescope. Saturn also has large number of satellites. Its density is less than that of water.

3. Uranus: It is the outermost planet of solar system. It can only be seen with large telescopes. It rotates from east - west. The most remarkable feature of Uranus is that it has highly tilted rotational axis. As a result, in its orbital motion, it appears to roll on its side.

4. Neptune: It is also an outer planet. It too can only be seen with large telescope.